My experiences and views on Oracle Database

ASSM and PCTFREE

From 9i, Oracle introduced Automatic Segment Space Management (ASSM) as a replacement of freelists management.In a locally managed tablespace, there are two methods by which Oracle manages the Segment Space:- Automatic and Manual.Manual segment space management uses “FREELISTS” to manage the free space in the segment whereas the Automatic segment space management uses “BITMAPS”.From 10g onwards, Automatic Segment Management is by default for all new permanent,locally managed tablespaces.

ASSM, completely eliminated the need to specify PCTUSED,FREELISTS and FREELIST GROUPS storage parameters for the objects created in the tablespace.Lets check it out.